Study On Physical And Mechanical Properties Of Sandstone In Fugu Region Of Northern Shaanxi Under The Conditions Of Freeze-thaw Cycle

The main rocks in Fugu region of Northern Shaanxi are sandstone and mudstone whichhave bad weathering resistance, poor mechanical properties. Because of the long frost periodand large diurnal temperature in this region,Freeze-thaw cycles have an obvious impact onrock weathering of slope and the physical and mechanical properties,so the freeze-thaw cyclewill surely become an important factor in Slope Stability Analysis. This article select thesandstone as its object of study,select freeze-thaw cycles and temperature as the two controlconditions. In other words,the physical and mechanical properties tests were did in differentfreeze-thaw cycles and extreme temperatures,then using least squares to analyze the data toexplore changes in their physical and mechanical properties of sandstone under controlledconditions.Studies have shown that: In the process of freeze-thaw cycles with the increasing numberof freeze-thaw cycles, sandstone quality are generally shown a downward trend, but thequality of the reduced rate is not a fixed value; In the process of freeze-thaw cycles with theincreasing number of freeze-thaw cycles, the volume of sandstone volatile ups and downs oftrend, but wave around certain value.At the same time volume is affected by the rock itselfdamage degradation,along the direction of the bedding rock fracture which will affect thevolume change, meanwhile the deterioration and damage started in maroon sandstone ormaroon sandstone and gray sandstone transition zone; In this test cycle20-23times began todamage degradation,the damage degradation are mainly on fracture mode,accompanied bypeeling off mode. In the aspect of mechanical properties of sandstone,uniaxial compressive strength will decrease as a whole with the increase of number of freezing and thawing, butlocal fluctuated, with a modest increase;tensile strength with the increase of number offreezing and thawing decreases at the first, and add at the last;Cohesive force of value of thesandstone with the increase of number of freezing and thawing in the trend of change is verysmall to reduce, increase after;Angle of internal friction values have a very small decreasetrend.This article is the first time to study the physical and mechanical properties of thesandstone in Fugu region of Northern Shaanxi under the condition of freeze-thaw cycles,which has great important theoretical and realistic significance.